Nihonium is a synthetic, highly radioactive p-block element in group 13. It was first produced by RIKEN (Japan) and exists only briefly as heavy isotopes, decaying by alpha emission.
Nihonium (Nh) is a synthetic p-block element with atomic number 113. It belongs to Group 13 (the boron–aluminium–gallium–indium–thallium family) in period 7. Because it does not occur in nature, it is produced atom-by-atom in particle accelerators.
Nh was first reported by RIKEN (Japan). In the lab it is created in fusion–evaporation reactions where a heavy target is bombarded by a medium-mass ion. A stylized route is:
\(^{209}\mathrm{Bi}(^{70}\mathrm{Zn},\,x n)\,^{279-x}\mathrm{Nh}\)
Nh has also appeared as a decay descendant from heavier nuclei made with calcium beams on actinide targets.
Newly formed Nh atoms recoil out of the target and are separated in-flight, then implanted into position-sensitive detectors. Identification relies on time-correlated decay chains with characteristic energies and lifetimes, typically alpha decay:
\(^{A}_{113}\mathrm{Nh} \;\xrightarrow{\alpha}\; ^{A-4}_{111}\mathrm{Rg} + \alpha \;\to\; \cdots\)
Only a few short-lived isotopes near mass numbers \(\sim 278\text{–}286\) have been observed. Their half-lives are typically milliseconds to seconds (some reaching tens of seconds), which is just long enough for decay-chain identification and, rarely, single-atom chemistry tests.
By analogy with thallium (Tl), Nh is predicted to favor the +1 state in condensed-phase chemistry, with +3 accessible under strongly oxidizing conditions. The preference for +1 is strengthened by relativistic effects that stabilize the 7s electrons and split the 7p subshell.
A commonly cited configuration is [Rn] 5f14 6d10 7s2 7p1. Relativistic stabilization of the 7s pair and splitting of 7p (\(7p_{1/2}\) vs. \(7p_{3/2}\)) help explain the expected dominance of the +1 oxidation state (an “inert-pair–like” effect).
Direct aqueous chemistry is not established due to extreme scarcity. Theory and single-atom gas-phase approaches suggest monovalent species (e.g., NhCl) and possibly oxohalides under strongly chlorinating/oxidizing conditions. Any such observations would be from thermochromatography or rapid on-line separation, not bulk experiments.
Experiments produce only a few atoms that decay quickly. This prevents preparing macroscopic samples to measure properties like density, melting point, or crystal structure. Most property estimates are therefore predictions from relativistic quantum calculations and periodic trends.
Yes. Nh is a radiotoxic heavy element. Although handled only in atom-scale amounts, research requires remote manipulation, high-vacuum separators, shielding, HEPA-filtered ventilation, dosimetry, and compliant radioactive-waste procedures.
Production (stylized fusion–evaporation):
\(^{209}\mathrm{Bi}(^{70}\mathrm{Zn},\,n)\,^{278}\mathrm{Nh}\)
Generic decay step:
\(^{278}\mathrm{Nh} \;\xrightarrow{\alpha}\; ^{274}\mathrm{Rg} + \alpha\)